<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>单位ex的一些用法</title>
    <style>
        p{
            font-size:2ex;
            background-color: fuchsia;
            line-height: 150px;
        }
        h3{
            /*font-size:35px;*/
            line-height: 50px;
            background-color: #cccccc;
            /*vertical-align: middle;*/
        }
        h3 span{
            font-size: 35px;
            vertical-align: baseline;
        }
    </style>
</head>
<body>
<p>你好</p>
<h3><span>你好</span></h3>
</body>
</html>